1. Field of the Invention
The present invention pertains to nonionic surfactants. More particularly, the present invention pertains to petrochemical-free nonionic surfactants. Even more particularly, the present invention pertains to nonionic surfactants derived from alkyl polyglucosides.
2. Prior Art
As is known to those skilled in the art to which the present invention pertains, a vast array of industrial chemicals are oil- or petrochemical-derived. One of the most important classes of such petrochemical-derived chemicals are surfactants or surface active agents and, especially, nonionic surfactants. There are an almost infinite number of nonionic surfactants available in the marketplace with varying properties ranging from low to high HLB, foamers, non-foamers, defoamers, wetting agents, emulsifiers, detergents and the like. The nonionic surfactants, have their properties tailored by virtue of both the hydrophile and hydrophobe as well as the hydrophobe-hydrophile balance imparted thereto during the synthesis thereof. By tailoring not only the hydrophile and the hydrophobe, per se, but the hydrophile-hydrophobe balance, the inherent properties of the resulting chemical can be prescribed to meet the exigencies of the situation and the desired result.
Ordinarily, the hydrophobe or water-insoluble portion of the surfactant is derived from two main sources. Traditionally, the aromatic hydrophobes, such as the alkylphenol and the diphenylethers which are petrochemical-derived comprise the first class of hydrophobes.
The second source or class of hydrophobes is the “naturally occurring” hydrophobe. These comprise a fatty alkyl chain. Traditionally, fatty acids and their derivatives, such as fatty alcohols, fatty amides and fatty amines, which are “naturally occurring,” ordinarily define the second group. Concededly, some fatty alkyl hydrophobic compounds are petrochemical-derived, such as the oxo-alcohols, but the vast majority are naturally occurring.
There is known at least one natural terpene-derived hydrophobe but which has been propoxylated to increase hydrophobicity, thereby negating the “naturally occurring” nature of such a surfactant.
It is also theorized that a Guerbet alcohol may define a potential source of hydrophobe which can be naturally occurring or which can be petrochemical-derived. Examples of Guerbet alcohols include, for example, those derived from short chain mono-alcohols, i.e. C6 to C10 alcohols.
The other component of a nonionic surfactant is the hydrophile. The most common hydrophile for a nonionic surfactant is obtained by a polymerization addition of an alkylene oxide, such as, for example, ethylene oxide and/or propylene oxide or other lower alkylene oxide to the hydrophobe. The oxide addition is either random or sequential. In any event, though, all alkylene oxides are petrochemical-derived.
In seeking alternate natural sources of hydrophilicity, the art has reported two significant examples thereof. First, there are the glucosamides. These are well known and used regularly in hand dish detergents. Similarly, the gluconic acid-derived surfactants, such as the glucamates which are commercially available from, example, Amerchol, are widely known. In either event, the glucosamides and the gluconic acid-derived surfactants have as their starting material basic naturally occurring sugars, i.e., glucose.
There is presently known and commercially available certain sugar-derived (glucose and sucrose) surfactants having a C8-16 fatty alcohol hydrophobe and a glucose hydrophile. These compounds are known as alkyl polyglucosides (APGs). They are well-known and commercially available from a variety of sources including Cognis, Akzo Nobel, and Uniqema.
APGs can be represented by the following formula: The APGs are petrochemical-free. They provide excellent detergency and are excellent foamers. However, because of the structure of the hydrophile, their hydrophilicity cannot be readily controlled.
Hydrophilicity is created by the addition of oxygen atoms to the hydrophobe. With APGs, oxygen atoms are added as hydroxyl groups, i.e. —OH. Thus, each glucose unit added to the alkyl portion of the surfactant adds three to four hydroxyl groups and the attendant increase in hydrophilicity. This is to be contrasted with typical ethoxylated surfactants where hydrophilicity is generated by adding single oxygen atoms as ether groups which are added individually to the polymer, thus, enabling control of the degree of hydrophilicity. It is to be appreciated that if it were possible to control the hydrophilicity of an APG-based surfactant that a major advance would be provided and it is to this to which the present invention is directed.